In the prior art, a warning device for a vehicle that warns a driver of presence of an object passing near the own vehicle is known (for example, see Patent Reference No. 1). In this warning device for a vehicle, a time of a collision between the own vehicle and the object (time-to-collision) or a distance thereof (distance-to-collision) is detected, and a display depending on the detection result is displayed on a display device. Therefore, it is possible to warn a driver of presence of the object by the display depending on the time of a collision between the own vehicle and the object or the distance thereof.